Liquid filling machine



1969 w. H. MARLOW ET AL 3,420,282

LIQUID FILLING MACHINE Filed June 2, 1960 Sheet of 2 Q Q i O0 O0 N//OO-OO INVENTORS. W/l. L IA M HE NR) MARL OW MATTHEW HENRY MA RONE Y SAMUELREID STEVENSON ATTORNEY 1969 w. H. MARLQW ETAL 3,420,282

LIQUID FILLING MACHINE Filed June 2, 1966 Sheet 5 of 2 Fa. F- E m PUMPuaro r l VALVE no v mom SENSOR e O 0- 70 VALVE 3/ INVENTORS. WILL/AMHENRY LOW MATTHEW HENRY ARONEY SAMUEL REID STEVENSON ,JZMW

- ATTORNEY United States Patent 9 Claims ABSTRACT OF THE DISCLOSURE Aliquid filling machine for vials or other containers is provided with areservoir which is mounted on a rotating table, the reservoir beingconnected to a source of sterile air. From the reservoir a conduit leadsto a filling valve of the elastomer tube pinched type. Liquid is fedfrom the bottom of the container and the pressure at the filling nozzlesis sensed and controls the supply of compressed sterile air to thecontainer. This results in maintaining constant the pressure at thefilling nozzles regardless of changes in level of liquid in thereservoir and hence changes in hydrostatic pressure. As the table turns,vials or other containers which are loaded on the table at one pointpass successively below the filling nozzles. Their position is sensed byradiations so there is no contact with the container and no danger ofknocking it over. When a container is properly located, an electriccounting device is started which opens the pinch on the filling nozzletube and counts a certain predetermined period of time which determinesthe amount of liquid filled into each vial. At the end of the time thetube at the filling nozzle is pinched closed and the table moves tobring another container into position.

Background of the invention Pharmaceutical liquids which have to befilled into containers, often small containers such as vials, present anumber of practical problems. These liquids require maintenance ofsterility and avoidance of contamination and also require that each vialor container receive a definite amount of liquid. It has been proposedin the past to use a pump which is similar to a syringe and which can beprecalibrated to draw up a definite volume of liquid from a reservoirand deliver it into the waiting container. This method is unsatisfactoryfrom the standpoint of sterility because the plunger element of the pumpis exposed to the atmosphere on the out stroke, which can result incontamination, and the moving parts of the pump tend to wear and producesmall particles of friction, which may contaminate the liquid fillingeven though in some cases they may not be septic. The pump method alsorequires numerous valves, and the metering of the filling mechanismrequires frequent maintenance. This is bad enough with pure liquids, butit is much worse if the product is a suspension, because the particlesin the suspension tend to accumulate in valves and the like. Also, whenviscous, tacky liquids are being filled, evaporation of the solvent mayleave a residue in the pump mechanism. Generally this clogging of thepump or valves causes a breakdown of the system and requires cleaningout at the least and often replacement of damaged parts. Both are economically undesirable.

Another aspect of filling operations with pumps or metering devices isthat essentially they are two-step processes; thus the pump is filledfrom the reservoir by the out stroke and then the liquid dose expelledinto the package by the in stroke. Similarly, in metering fillingmachines the meter chamber is first filled to the set volume and thisvolume is then delivered to the package container. In both cases thereis not a continuous flow but an interrupted flow, all the way back tothe reservoir of the liquid. This interrupted operation adverselyaffects efliciency.

Another form of filler involves a pump in the form of a screw in aflexible conduit and a valve body which is periodically opened for atimed interval. The timing involves mechanical operation and exactlyreproducible filling is not possible, variations of as much as 27% beingencountered. The presence of valves, of course, also involves theproblems of plugging and contamination referred to above. Except thatthere is timed filling, the operation is no diiferent from the otherapparatus described above.

Summary of the invention According to the present invention a reservoirof liquid is maintained with accurate and definite pressure on a conduitor conduits leading to container filling nozzles. The reservoir may be alarge one containing the original bulk material to be filled andpressure maintained by slightly compressed air pumped into the liquid,or in the case of products which react with constituents in the air, thegas may be any inert gas, such as nitrogen. It should of course besterile. The reservoir can also be a smaller reservoir fed from a largerbulk supply by controlled pumping. The intermediate reservoir, however,should have a sterile atmosphere of air or other slightly compressedgases which serves to prevent surges acting as a cushion. In any event,the conduit or conduits leading to filling nozzles from the reservoirare flexible or deformable at at least one point. Obviously, of course,the apparatus is sterilized before starting and additional precautionscan be taken in the usual manner by providing a sterile area and by theuse of sterilizing radiation, such as ultraviolet light of germicidalwavelengths.

Instead of providing valves or anything else which extends into theinside of the filling conduit, the flexible or deformable portion ismechanically pinched for an accurately predetermined time interval. Thisshuts otf flow while a vial is moved into position by conveyor belts,rotary filling tables, or other conventional means, and then the conduitis fully opened for the predetermined time, thus filling a vial orcontainer with an accurate dose of liquid. Then the conduit is pinchedtogether mechanically, the flow ceases and does not resume until anothervial is in filling position.

It will be noted that in the present invention the filling conduit isfree from valves or other fittings in which residues can settle, andwhen it is filling the conduit is fully open. At the same time, nothingmoving is introduced into the conduit and contamination from wear andtear is eliminated, or so greatly reduced over that encountered inpumping and metering systems that it no longer presents a real problem.

While the filling operation is; continuous, in most cases there will befinite runs, for example an eight-hour shift. When the machine is notoperating or has been disassembled and sterilized for a changed liquid,it is very easy to replace the filling conduit or the deformable portionthereof. Usually the deformable portion will be of a suitable elastomer,such as rubber, neoprene, nylon, and the like, which can be replaced atintervals, as they are cheap and can be thrown away after a suitableinterval Without any significant increase in overall cost. This is anadded advantage of the present invention, as it permits periodicreplacements of a very cheap element. Deformable conduits have far lesswear and tear than pumps, but of course they do not last forever, andthe possibility of periodic replacements long before they have worn outrepresents a very attractive and efficient procedure and constitutes,therefore, one of the practical operating advantages of the presentinvention.

It should also be noted that deformable conduits can be of materialswhich are readily sterilized, have smooth surfaces, and are inert tomost liquids. It is an advantage of the invention that the use ofdeformable conduit sections automatically provides some or all of theabove advantages. This represents a very fortunate situation as often animproved machine is a compromise in which in order to obtain one desiredresult there may be offsetting disadvantages. In the case of the presentinvention there are not offsetting disadvantages, so that theimprovement is obtained without paying the price of other drawbacks.

It will be seen that the measuring out of the filling does not involveprecise adjustment of valves. In other words, it is not obtained bythrottling or back pressure. The filling conduits, except for thenozzles, as will be described below, do not introduce any substantial ormeasurable back pressure. Therefore, as far as the conduits areconcerned all that is necessary is maintenance of reasonably constantpressure in the conduits. The nozzles themselves, however, usually havesmall openings, and it is practi cally impossible to maintain thesecompletely uniform. In other words, the nozzles will create a certainamount of back pressure and this will be slightly different withdifferent nozzles. When filling large final containers, such as forexample a 200 ml. container, the variation in back pressure betweennozzles, which is quite small but not zero, can be disregarded as itwill constitute too small a percentage of the normal filling to besignificant. For example, if the variation in nozzles with constanttiming of the opening of the deformable portions of the filling conduitscreated a variation in volume of 1 ml. or less, this would be so small apercentage that it need not be taken into consideration. However, withsmall containers, such as 2 ml., the variation may be suflicient to beof significance. For example, a variation of .2 m1. would be In such acase the machine can be calibrated by varying the time in the preferredform with electronic counting for the different nozzles to produce anexact amount. Timing circuits, in which the count is either withseparate counting circuits or more economically with separate pick-offsin the case of multiple filling nozzles, can be precisely adjusted. Thisis an additional advantage of the present invention in its preferredmodification using electronic counting circuits for determining thetiming intervals. The precision with which counts can be varied andaccurately maintained is orders of magnitude greater in standardcounting circuits than the permissible variation in the volume filled.It is thus possible to calibrate exactly within the limits desired, andthis calibration will hold because timing circuits are extremely stable.Ordinarily with multiple nozzles calibration need only be made atintervals, for example when starting up at the beginning of a shift orwhen there is a change in material to be filled. The calibration takes avery short time and is extremely precise, and this constitutes anadditional practical advantage of the preferred modification of thepresent invention. The same possibility of varying filling volume withprecision by varying electrical counts also permits changing rapidly andaccurately from one size container to another. There is no delicateadjustment of throttling valves and the like, and the time interval,once set, remains constant.

While there is an advantage in flexibility and versatility when thetiming of the opening and pinching of the deformable sections of fillingconduits is effected by electronic timing circuits, in a more broadaspect the invention is not limited thereto and any other intervaltiming may be used provided it is accurate. The accuracy is an importantand essential feature of the present invention, but the exact electronicor other constructions of the timing intervals is not and any suitableaccurate timing mechanism may be used. However, because of the extremeprecision of electronic counting circuits and their ing operation; orthe filling nozzles may move with the vials, for example through asuitable arc on a rotating container feeding device, which eliminatesintermittent motion and lends iself to automatic feeding of emptycontainers and removing of filled containers. The continuous method,therefore, has practical operating advantages which more than offset itssometimes slightly higher constructional cost. Both types of fillingwill be specifically described below, but it should be understood thatthese are just examples of the basic requirement that the fillingnozzles at the end of the conduits be accurately maintained over themouth of the vial or container being filled during the fillingoperation. The flexibility in choice of actual mechanism is an addedpractical advantage.

Brief description of the drawings FIG. 1 is a partially diagrammaticsectional representation of a continuous filling modification of thepresent invention;

FIG. 2 is a similar representation of an intermediate reservoir type;and

FIG. 3 is a simplified electric circuit for starting and stopping a run.

Description of the preferred embodiments FIG. 1 shows a bulk container 1with the liquid to be filled at 2 and an air space above at 4.Surrounding the reservoir is a rotating table 19, which is shown partlybroken away to illustrate the loading of only one via] at a time inorder not to complicate the drawing. The table and the reservoir on itare continuously though slowly rotated about an axis 18 by conventionaldrive, (not shown). A tube 5 extends to the bottom of the reservoir 1and leads, through an isolating diaphragm 16, to a pressure sensor 8provided with a gauge 9. This sensor is of conventional design and istherefore shown only diagrammatically.

A source of substantially sterile air or other gas under pressureconnects through an ON and OFF valve 10 into the space 4 above theliquid 2 in the reservoir. This valve is actuated electrically from thepressure Sensor 8 and, of course, opens the valve when the pressuresense drops below a predetermined value and closes when it has reachedit again. Needless to say, the compressed air container is sufiicientlylarge and maintained at a sufficient pressure so that the presetpressure on the sensor 8 is maintained even when the liquid in thereservoir has reached the bottom. It will be seen that the sensor 8 isat substantially the level of the tube 7 leading to the filler, and asboth the tube 6 and the tube 5 lead from the bottom of the tank 1, thesensor senses a pressure which is the sum of the gas pressure in thespace 4 and of the hydrostatic head of the liquid 2 to be filled. Inother words, pressure is maintained at the nozzle constant regardless ofthe level of liquid in the tank 1.

Pipes 6, only one of which is shown in the figure, extend also about tothe bottom of the liquid in the reservoir 1. These pipes are developedinto deformable conduits 7 leading to filling orifices 20, shownpositioned over a vial 3 to be filled. Just above the filling nozzle 20is a compression sleeve actuated by two solenoids 12 which can compressit to pinch the deformable tubing 7 closed or to open it wide. Thetubing is, of course, of suitable elastomer so that when the solenoids12 are in the unpinched position, which is shown in the drawing, theinside of the tubing 7 is fully opened. When a vial 3 is moved intoposition under a particular nozzle 20, an electric eye 17 turns on thecounting circuit 15, which is of conventional design and thereforeillustrated diagrammatically. As the electric eye senses the position ofthe vial by radiation without mechanical contact therewith, no force isexerted on the vials which would tend to tip them over. The counterreceives an input through wire 14 from an accurate pulse generator oroscillator 13, which is also of conventional design and indicateddiagrammatically. It may, for example, be a crystal controlledoscillator which oscillates at a suitable frequency. Pick ofis for eachpair of solenoids 12 are shown as going out through wires 21 from thecounting circuit. These wires are shown broken and are connected totheir respective solenoids through conventional slip rings on therotating loading table (not shown). In order not to complicate thedrawing, only one set of wires 21 is shown, but there are of course aset constituting a pick off for each pair. The count for each pick offis shown on dials 22 which indicate through conventional indicators thenumber of counts for each pickup. To simplify the drawing only eightcounting dials are shown, although in a large machine the table wouldordinarily be provided with more than eight filling nozzles in one ormore rows. Also, two separate solenoids 12 are shown for simplicity inunderstanding the operation of the invention. Commercial solenoids areknown in which the pinching is effected in a single structure, but thedrawing is intended to illustrate the operation of the present inventionrather than to show exact design of standard solenoid pinch valves, theparticular mechanical and electrical design of which forms no part ofthe present invention.

As has been mentioned above, when a vial 3 comes into position under itsfilling nozzle at a loading station on the table 19, which isillustrated on the drawing, the electric eye 17 turns on the countingcircuit for the particular pair of solenoids 12 and they open, theposition shown on the drawing. Now as the table turns and with it thenozzles and vials, material flows through the nozzle 20 for a timedetermined by the particular number of counts set for this particularpickup. Any desired number can be set by conventional selectors on thetiming circuit console 15. As these are standard items they are notshown, as their particular design again forms no part of the presentinvention. As has been described above, a different number of counts canbe set for the different nozzles 20; or if the nozzles happen to beuniform or if the volume of material filled is so large that it is notnecessary to adjust individual nozzles for a particular count, the flowcontinues until the particular pickup registers the pre-set number ofcounts. The solenoids 12 are then moved together, shutting off the flow,and the filled via] 3 is then removed. The conventional timing console15 automatically resets each pick off when the pre-set number of countshave been counted, and it is of course ready to start again when anotherempty vial is placed under its particular nozzle at the point indicatedon the drawing. Since the pressure in the air space 4 is maintainedconstant, or rather the pressure of liquid in the tube 6, for the latteris determined by a combination of the pressure in the air space 4 andthe hydraulic head of liquid 2, the filling of each vial is precisebecause the flow has continued for the accurately pre-set time interval.

If a vial fails to be put under its filling nozzle, the electric eye 17does not send out a signal and, therefore, the pickup for thisparticular pair of solenoids is not actuated and accordingly they remainclosed until the table has made another revolution and a vial isactually positioned under the filling device. This prevents filling ifthere is no vial there, which would spill liquid or other material overthe loading table. It should be noted that in the modification shown inFIG. 1 the vials and filling nozzles move continuously. Hence thispresents advantages and permits maximum filling speed. However, themechanism is somewhat more complicated and so the machine may be moreexpensive. Where filling lines are in existence using a conveyor andintermittent blocking of vials under stationary nozzles, such operationcan be effected, but of course the movement of the vials is thenintermittent; the possibility of a vial falling on its side duringfilling is not completely excluded and, therefore, normally lower speedsare used. However, the fixed nozzles, fixed conduits and unmovingreservoir are simpler structures and, as has been pointed out above, amore economical machine is possible, particularly if the conveyingmachinery is already in existence, as is often the case where othertypes of filling mechanisms have been used before and are replaced withthe improved form of the present invention. Needless to say, the vialsdo not resume intermittent motion the instant the solenoids pinchclosed, and a very brief hesitation permits any last drops on a nozzleto drop into the container. This is simply a matter of timing of theintermittent motion and is not an unknown device. It is mentioned heremerely to illustrate that when the principles of the present inventionare incorporated in more or less normal or standard filling mechanisms,no undesirable drawbacks are introduced.

In most container filling machines, such as for example for fillingvials, it is common to provide automatic stoppering machines whichintroduce stoppers or other closures on the filled vials. The mechanismof these devices is not affected at all by the present invention, andtherefore they have not been shown in the drawing. In any automaticfilling line, however, they will normally be used because of the greatsaving of time effected and the desirable elimination of further manualhandling, with possible contamination or compromise of sterility.

It will be noted that no human hands touch the vials or any other partof the machine during the filling operation. Only in loading andunloading may manual contact with the outside of the vial take place,and even this can be effected automatically, as is a common procedurewith many filling systems. Sterility, therefore, can be maintained andthere is no danger of any undesired septic contamination. As with mostoperations where sterility is required, the room, working space, and themechanism is normally maintained in a sterile or substantially sterileenvironment, for example by suitable germicidal lamps and the like. Itis an important advantage of the present invention that completesterility can be maintained, but of course the environment of the roomis not changed by the present invention. Also, it is possible to use thepresent invention for filling of materials which do not have to befilled under sterile conditions. This adds a flexibility to the presentinvention, but of course its greatest and most important single field isin sterile filling.

FIG. 2 illustrates a different modification for transfer of liquid tothe filling conduits. It may be used either with a rotating, continuousfilling table or with intermittently actuated movements. Therefore, onlythe portion up to the tube 7 is illustrated. Similar elements, such aspressure sensor and the like, are given the same numbers as in FIG. 1.

A large bulk container, such as a tank or drum containing 1,000 or moreliters, is shown at 23. From this drum a tube 24 extending to the bottomleads to a pump 25, which may be of conventional design and is thereforeshown only diagrammatically. The drive of the pump is through anelectric motor, (not shown). The output of the pump 25 passes through asterile filter 26 of conventional design, which is also showndiagrammatically. The filtered output passes through a valve 27, whichis'of the ON and OFF type and, except for its design to handle liquid,is similar to the valve 10 in FIG. 1. As in that figure it is controlledby a sensor 8 which connects to the bottom of an intermediate reservoir28, which may be of much smaller size, for example a few liters. As inFIG. 1, the sensor 8 responds to a pressure which is the sum of thepressure in the air space 4 and the hydrostatic head on the liquid inthe reservoir 28. Accordingly, it does not change with variations oflevel in the reservoir. The conduit 29 from the valve 27 also extends tothe bottom of this reservoir, which is provided with an air space 4which performs an analogous function to the air space 4 in FIG. 1,namely to provide for smooth pressure maintenance, though the mechanismby which the pressure is produced is slightly different, as will bedescribed below.

As has been mentioned, the pipe 6 and conduit 7 are essentially the sameas the corresponding elements in FIG. 1 and lead through a deformableportion and timed pinching means to filling nozzles. These are not shownas they are no different from the corresponding elements in FIG. 1. Ofcourse a number of tubes 6 or a number of conduits 7 branching off froma single tube 6 are provided, one for each filling nozzle. Themodification of FIG. 2 lends itself particularly to stationary fillingnozzles, although the reservoir 28 may be rotated in the same manner asis described in FIG. 1, the inlet tube 29 of course being axial andrequiring seal 30.

When a vial is under a particular filling nozzle, the electric eye orother sensor senses it in the same manner as in FIG. 1 and sends asignal to the counting circuit or pick ofi? for the particular nozzle.This opens the solenoids for the precisely determined time interval,exactly as described in connection with FIG. 1. There is, however, asmall difference in the manner in which the pressure in the conduit 7 ismaintained. Instead of maintaining it by air pressure, as shown in FIG.1, it is maintained by periodic pumping through the valve 27 which opensand closes in accordance with the changes of pressure resulting from theflow of liquid into the filling conduit 7. As the pressure is maintainedconstant, the valve 27 lets in liquid at approximately the same rate atwhich it is filled into containers. The air space 4, which is confined,performs its function as a surge preventer or cushion exactly as in FIG.1.

When the large bulk container 23 is empty, this is signalled either tothe operator or there is an automatic operation of the necessaryswitches, which will be described in more detail below in connectionwith FIG. 3. It should be noted, of course, that when the bulk container23 is empty, there is still liquid in the container 28, and it becomesdesirable to empty this container. The same may occur at the end of afilling operation, such as the end of a shift, even though the bulkcontainer 23 is not necessarily empty. This is effected by a second ONand OFF valve 31 which is connected to a source of compressed sterilegas and is also actuated from the sensor 8, as will be described inconnection with FIG. 3. FIG. 3 shows in schematic form a double pole,double throw switch. The movable portion of one of the pairs of poles isconnected to the sensor 8. The other movable pole is connected to asource of power, shown on the diagram as 110 volts. When the switch isin its upper position, it will be seen that power is connected to themotor which drives the pump 25 and signals from the sensor 8 areconnected to the valve 27, producing the operation which has beendescribed above. Now, however, if it is the end of a shift and it isdesired to empty reservoir 28, the switch is thrown to its lowerposition, which therefore stops liquid from the sterile filter 26 flowsback into the container 23 through its by-pass, which is standard andwhich is not specifically shown in the diagrammatic representation ofFIG. 2. The other pole of the switch is now connected to valve 31, ashas been described, and sterile air or other gas is introduced throughthe conduit 29 at the rate called for by the sensor 8 in order to fillthe remaining liquid from the reservoir 28 into the containers. Thisresults in emptying the container, which can be signalled by aconventional signal or noted by the operator through a sight glass, andthe whole operation is shut down. The small reservoir 28 can then beconveniently removed and cleaned and resterilizecl for the next run.This leaves the container 28 full of air or other sterile gas, and whenthings are started up on the next run, liquid is pumped in by the pump25 until the air in the space 4 is compressed to the pressure for whichthe sensor 8 is set. Another operation follows as described above.

We claim:

1. An unthrottled liquid filler for containers, suitable for sterilefilling, comprising in combination:

(a) a reservoir of liquid to be filled,

(b) at least one container filling conduit extending into the liquidsubstantially to the bottom of the reservoir and leading to a fiifagnozzle,

(c) means for sensing the total pressure of liquid in the conduitincluding the component of pressure due to hydrostatic head of liquidand for maintaining the liquid in the conduit at a predeterminedpressure, regardless of varying liquid levels,

(d) the conduit having at least a section which is elasticallydeformable, and

(e) means for pinching the deformable section closed and opening it tounrestricted flow for a precisely predetermined time interval whereby apredetermined volume of liquid flows through the conduit each time thedeformable section is unpinched.

2. A liquid filling machine according to claim 1 in which the means forpinching the deformable section is an electrical means and the timeinterval is determined by electronic counting circuit.

3. A liquid filling machine according to claim 2 in which means areprovided for loading containers under the nozzles with noncontact,radiations actuated sensing means sensing when a container is properlypositioned and means actuated by said sensing means for initiatingfilling by opening the pinching means and starting the electroniccounting for the particular nozzle in question whereby if a container isnot loaded under a particular nozzle, the filling cycle for that nozzledoes not occur and spillage is prevented.

4. A liquid filling machine according to claim 2 in which there isprovided a plurality of filling nozzles and the counting circuits foreach nozzle are adjustable to provide for different counts for differentnozzles.

5. A liquid filling machine according to claim 1 in which pressure inthe filling conduits is maintained by pressure controlled pumping meansfrom a large bulk container.

6. A liquid filling machine according to claim 2 in which pressure inthe filling conduits is maintained by pressure controlled pumping meansfor a large bulk container.

7. A liquid filling machine according to claim 6 comprising a source ofsterile gas under pressure and selectable means for introducing eithersterile gas or liquid into the top of the reservoir.

8. A liquid filling machine according to claim 3 in which the means forloading containers under the nozzles comprises a rotating plate on whichvials can be mounted and means for mounting the reservoir coaxially withthe rotating plate whereby when the plate rotates the reservoir rotatestherewith.

9. An unthrottled liquid filler for containers, suitable for sterilefilling, comprising in combination:

(a) a reservoir of liquid to be filled,

(b) at least one container filling conduit extending into the liquid inthe reservoir and leading to a filling nozzle,

(c) means for maintaining the liquid in the conduit at a predeterminedpressure,

(d) the conduit having at least a section which is elasticallydeformable,

(e) means for pinching the deformable section closed and opening it tounrestricted flow for a precisely predetermined time interval whereby apredetermined volume of liquid fiows through the conduit each time thedeformable section is unpinched, and

9 10 (f) means for loading containers under the nozzles 2,405,998 8/1946Buttner et a1 141-95 X comprising noncontact, radiation actuated sensing2,751,114 6/1956 Greaves 222--396 X means sensing when a container isproperly posi- 3,049,142 8/1962 Oliver 25l +7X tioned and means actuatedby said sensing means 3,065,775 11/1962 Keyes 141-160 X for initiatingfilling by opening the pinching means, 5

and the means for providing unrestricted flow for a preciselypredetermined time interval comprise elec- FOREIGN PATENTS trical meansfor pinching the deformable conduit section and electronic countingmeans for maintaining the deformable section in unpinched condition 10during a filling cycle, both electrical means being actuated by themeans for sensing the proper positioning of a container under thenozzles. HOUSTON BELL Pnmary Exammer' References Cited UNITED STATESPATENTS US. Cl. X.R.

2,351,392 6/1944 Biner 141-151 251-7; 222396

